scsi: qla2xxx: Warn if done() or free() are called on an already freed srb

[ Upstream commit c0014f94218ea3a312f6235febea0d626c5f2154 ]

Emit a warning when ->done or ->free are called on an already freed
srb. There is a hidden use-after-free bug in the driver which corrupts
the srb memory pool which originates from the cleanup callbacks.

An extensive search didn't bring any lights on the real problem. The
initial fix was to set both pointers to NULL and try to catch invalid
accesses. But instead the memory corruption was gone and the driver
didn't crash. Since not all calling places check for NULL pointer, add
explicitly default handlers. With this we workaround the memory
corruption and add a debug help.

Link: https://lore.kernel.org/r/20200908081516.8561-2-dwagner@suse.de
Reviewed-by: Martin Wilck <mwilck@suse.com>
Reviewed-by: Arun Easi <aeasi@marvell.com>
Signed-off-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/scsi/qla2xxx/qla_init.c b/drivers/scsi/qla2xxx/qla_init.c
index 2861c636dd651c678e4211adbe3b50ff9f70bee7..f17ab22ad0e4a47d9c4f685d78a16ea1977d677e 100644 (file)
--- a/drivers/scsi/qla2xxx/qla_init.c
+++ b/drivers/scsi/qla2xxx/qla_init.c
@@ -63,6 +63,16 @@ void qla2x00_sp_free(srb_t *sp)
        qla2x00_rel_sp(sp);
 }
 
+void qla2xxx_rel_done_warning(srb_t *sp, int res)
+{
+       WARN_ONCE(1, "Calling done() of an already freed srb %p object\n", sp);
+}
+
+void qla2xxx_rel_free_warning(srb_t *sp)
+{
+       WARN_ONCE(1, "Calling free() of an already freed srb %p object\n", sp);
+}
+
 /* Asynchronous Login/Logout Routines -------------------------------------- */
 
 unsigned long

diff --git a/drivers/scsi/qla2xxx/qla_inline.h b/drivers/scsi/qla2xxx/qla_inline.h
index 1fb6ccac07ccd152e3bfcf0d5e0dc6442ae58177..26d9c78d4c52c0af0c4d321da5528fbfc774e0f9 100644 (file)
--- a/drivers/scsi/qla2xxx/qla_inline.h
+++ b/drivers/scsi/qla2xxx/qla_inline.h
@@ -207,10 +207,15 @@ qla2xxx_get_qpair_sp(scsi_qla_host_t *vha, struct qla_qpair *qpair,
        return sp;
 }
 
+void qla2xxx_rel_done_warning(srb_t *sp, int res);
+void qla2xxx_rel_free_warning(srb_t *sp);
+
 static inline void
 qla2xxx_rel_qpair_sp(struct qla_qpair *qpair, srb_t *sp)
 {
        sp->qpair = NULL;
+       sp->done = qla2xxx_rel_done_warning;
+       sp->free = qla2xxx_rel_free_warning;
        mempool_free(sp, qpair->srb_mempool);
        QLA_QPAIR_MARK_NOT_BUSY(qpair);
 }